GEOCHRONOLOGY LAB FOR AN INTRODUCTORY PHYSICAL GEOLOGY COURSE

Experience indicates that student learning is facilitated by doing projects (rather than just hearing lectures or reading texts) and sharing the experience in a group. Six projects have been implemented for group learning about geochronology in an introductory physical geology lab course, with alternates in development. These projects have been successfully tested at two universities for several years, and are available online (www3.baylor.edu/~Vince_Cronin/PhysGeoLabs) as PDF files for copyright-limited use. Each project begins with a question, and students work toward answers by completing the project. The projects involve several skills that are emphasized throughout the lab course, including computation, graphing data, interpreting graphs, pattern recognition, experimentation, error and uncertainty, and interpretation of geologic maps and cross sections. While the projects are quantitative, they require no math skills that exceed the national standards for high-school graduates.

The first project involves interpretation of the sequence of geological events reflected in a geologic map and cross section. The second uses index fossils to define the age of various strata. The third gives the students practice in working with the enormous numbers needed to represent deep time by having them compute various analogs for geologic time (e.g., if the ~4.6 Ga span of Earth history was represented by the length of a 100-meter soccer field, the Precambrian would be ___ meters long...) In the fourth project, students work with the mathematics of isotopic decay to construct decay curves. The fifth involves the interpretation of a specimen's age using isotopic ratios and a decay curve. The sixth involves magnetic polarity stratigraphy. Alternates include construction of a geologic time scale using speciation/extinction data, estimating time intervals using sedimentation rates, and estimating the time needed to open the South Atlantic Basin.

Six projects are completed during a single lab period lasting one hour and 50 minutes. The projects are supplemented by an introductory text, web notes, and answers to some relevant frequently-asked questions that are accessible via our department website (www.baylor.edu/Geology/). Student reaction to these exercises has been quite positive.